The 50-100 ms Predictive Shadow
KRONOS-CTRL runs ahead of the real plant, holding a 50-100 ms forecast so controllers act on where the machine is going, not only where it is.
Running ahead of reality
The predictive shadow is KRONOS-CTRL advancing its coupled state faster than real time to hold a continuous 50-100 ms forecast of the machine. At any wall-clock instant the twin publishes both the current best estimate and a projection of the state 50-100 ms into the future under the current actuation plan. Controllers and the anomaly ensemble consume the projection, so they act on the developing situation rather than the already-past present.
Why this horizon
The 50-100 ms window is chosen to match the dynamics L3 governs: it is long enough to see a growing MHD mode, an eroding plug potential, or a developing thermal excursion in time to plan a response, and short enough that the twin's surrogates stay accurate over the rollout. The fastest events, sub-millisecond vertical instability, microsecond quench, are not the shadow's job; they belong to the L1 fast loops and the hardware failsafe. The shadow owns the millisecond-to-hundred-millisecond regime between them.
- Horizon: 50-100 ms of validated forward projection
- Purpose: give MPC and anomaly detection lead time to act
- Cadence: refreshed every twin step against fresh telemetry
- Boundary: does not encroach on L1 microsecond determinism
The shadow is only as good as its synchronization to the real plant: each step it is corrected toward the latest measurements so the forecast does not drift away from reality. The divergence between shadow and plant is itself monitored, a growing divergence is both a model-drift signal and an anomaly signal, since it means the machine is doing something the validated physics did not predict.
The MPC horizon is aligned to the shadow so the controller never plans further than the twin can faithfully predict; extending control ambition beyond the validated forecast would be exactly the kind of overclaim the L3 design forbids.